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Commit 10584211 authored by Ian Kent's avatar Ian Kent Committed by Al Viro
Browse files

autofs4: Add d_automount() dentry operation 



Add a function to use the newly defined ->d_automount() dentry operation
for triggering mounts instead of doing the user space callback in ->lookup()
and ->d_revalidate().

Note, to be useful the subsequent patch to add the ->d_manage() dentry
operation is also needed so the discussion of functionality is deferred to
that patch.

Signed-off-by: default avatarIan Kent <raven@themaw.net>
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent db372915

fs/autofs4/autofs_i.h

+30 −0
Original line number Diff line number Diff line
@@ -218,6 +218,36 @@ extern const struct inode_operations autofs4_direct_root_inode_operations; 
extern const struct file_operations autofs4_dir_operations;

extern const struct file_operations autofs4_root_operations;



/* Operations methods */



struct vfsmount *autofs4_d_automount(struct path *);



/* VFS automount flags management functions */



static inline void __managed_dentry_set_automount(struct dentry *dentry)

{

	dentry->d_flags |= DCACHE_NEED_AUTOMOUNT;

}



static inline void managed_dentry_set_automount(struct dentry *dentry)

{

	spin_lock(&dentry->d_lock);

	__managed_dentry_set_automount(dentry);

	spin_unlock(&dentry->d_lock);

}



static inline void __managed_dentry_clear_automount(struct dentry *dentry)

{

	dentry->d_flags &= ~DCACHE_NEED_AUTOMOUNT;

}



static inline void managed_dentry_clear_automount(struct dentry *dentry)

{

	spin_lock(&dentry->d_lock);

	__managed_dentry_clear_automount(dentry);

	spin_unlock(&dentry->d_lock);

}



/* Initializing function */



int autofs4_fill_super(struct super_block *, void *, int);

fs/autofs4/expire.c

+6 −0
Original line number Diff line number Diff line
@@ -300,6 +300,7 @@ struct dentry *autofs4_expire_direct(struct super_block *sb, 
			spin_unlock(&root->d_lock);

		}

		ino->flags |= AUTOFS_INF_EXPIRING;

		managed_dentry_set_automount(root);

		init_completion(&ino->expire_complete);

		spin_unlock(&sbi->fs_lock);

		return root;
@@ -408,6 +409,7 @@ struct dentry *autofs4_expire_indirect(struct super_block *sb, 
		expired, (int)expired->d_name.len, expired->d_name.name);

	ino = autofs4_dentry_ino(expired);

	ino->flags |= AUTOFS_INF_EXPIRING;

	managed_dentry_set_automount(expired);

	init_completion(&ino->expire_complete);

	spin_unlock(&sbi->fs_lock);

	spin_lock(&autofs4_lock);
@@ -479,6 +481,8 @@ int autofs4_expire_run(struct super_block *sb, 
	spin_lock(&sbi->fs_lock);

	ino = autofs4_dentry_ino(dentry);

	ino->flags &= ~AUTOFS_INF_EXPIRING;

	if (!d_unhashed(dentry))

		managed_dentry_clear_automount(dentry);

	complete_all(&ino->expire_complete);

	spin_unlock(&sbi->fs_lock);
@@ -516,6 +520,8 @@ int autofs4_do_expire_multi(struct super_block *sb, struct vfsmount *mnt, 
			ino->flags &= ~AUTOFS_INF_MOUNTPOINT;

		}

		ino->flags &= ~AUTOFS_INF_EXPIRING;

		if (ret)

			managed_dentry_clear_automount(dentry);

		complete_all(&ino->expire_complete);

		spin_unlock(&sbi->fs_lock);

		dput(dentry);

fs/autofs4/inode.c

+4 −0
Original line number Diff line number Diff line
@@ -252,6 +252,7 @@ static struct autofs_info *autofs4_mkroot(struct autofs_sb_info *sbi) 
}



static const struct dentry_operations autofs4_sb_dentry_operations = {

	.d_automount	= autofs4_d_automount,

	.d_release      = autofs4_dentry_release,

};
@@ -320,6 +321,9 @@ int autofs4_fill_super(struct super_block *s, void *data, int silent) 
		goto fail_dput;

	}



	if (autofs_type_trigger(sbi->type))

		__managed_dentry_set_automount(root);



	root_inode->i_fop = &autofs4_root_operations;

	root_inode->i_op = autofs_type_trigger(sbi->type) ?

			&autofs4_direct_root_inode_operations :

fs/autofs4/root.c

+149 −112
Original line number Diff line number Diff line
@@ -35,7 +35,6 @@ static long autofs4_root_compat_ioctl(struct file *,unsigned int,unsigned long); 
#endif

static int autofs4_dir_open(struct inode *inode, struct file *file);

static struct dentry *autofs4_lookup(struct inode *,struct dentry *, struct nameidata *);

static void *autofs4_follow_link(struct dentry *, struct nameidata *);



#define TRIGGER_FLAGS   (LOOKUP_CONTINUE | LOOKUP_DIRECTORY)

#define TRIGGER_INTENTS (LOOKUP_OPEN | LOOKUP_CREATE)
@@ -73,7 +72,6 @@ const struct inode_operations autofs4_direct_root_inode_operations = { 
	.unlink		= autofs4_dir_unlink,

	.mkdir		= autofs4_dir_mkdir,

	.rmdir		= autofs4_dir_rmdir,

	.follow_link	= autofs4_follow_link,

};



const struct inode_operations autofs4_dir_inode_operations = {
@@ -420,13 +418,12 @@ void autofs4_dentry_release(struct dentry *de) 


/* For dentries of directories in the root dir */

static const struct dentry_operations autofs4_root_dentry_operations = {

	.d_revalidate	= autofs4_revalidate,

	.d_release	= autofs4_dentry_release,

};



/* For other dentries */

static const struct dentry_operations autofs4_dentry_operations = {

	.d_revalidate	= autofs4_revalidate,

	.d_automount	= autofs4_d_automount,

	.d_release	= autofs4_dentry_release,

};
@@ -540,137 +537,187 @@ static struct dentry *autofs4_lookup_expiring(struct dentry *dentry) 
	return NULL;

}



/* Lookups in the root directory */

static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)

static int autofs4_mount_wait(struct dentry *dentry)

{

	struct autofs_sb_info *sbi;

	struct autofs_info *ino;

	struct dentry *expiring, *active;

	int oz_mode;

	struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);

	struct autofs_info *ino = autofs4_dentry_ino(dentry);

	int status;



	DPRINTK("name = %.*s",

	if (ino->flags & AUTOFS_INF_PENDING) {

		DPRINTK("waiting for mount name=%.*s",

			dentry->d_name.len, dentry->d_name.name);

		status = autofs4_wait(sbi, dentry, NFY_MOUNT);

		DPRINTK("mount wait done status=%d", status);

		ino->last_used = jiffies;

		return status;

	}

	return 0;

}



	/* File name too long to exist */

	if (dentry->d_name.len > NAME_MAX)

		return ERR_PTR(-ENAMETOOLONG);



	sbi = autofs4_sbi(dir->i_sb);

	oz_mode = autofs4_oz_mode(sbi);



	DPRINTK("pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d",

		 current->pid, task_pgrp_nr(current), sbi->catatonic, oz_mode);

static int do_expire_wait(struct dentry *dentry)

{

	struct dentry *expiring;



	active = autofs4_lookup_active(dentry);

	if (active) {

		dentry = active;

		ino = autofs4_dentry_ino(dentry);

	} else {

	expiring = autofs4_lookup_expiring(dentry);

	if (!expiring)

		return autofs4_expire_wait(dentry);

	else {

		/*

		 * Mark the dentry incomplete but don't hash it. We do this

		 * to serialize our inode creation operations (symlink and

		 * mkdir) which prevents deadlock during the callback to

		 * the daemon. Subsequent user space lookups for the same

		 * dentry are placed on the wait queue while the daemon

		 * itself is allowed passage unresticted so the create

		 * operation itself can then hash the dentry. Finally,

		 * we check for the hashed dentry and return the newly

		 * hashed dentry.

		 * If we are racing with expire the request might not

		 * be quite complete, but the directory has been removed

		 * so it must have been successful, just wait for it.

		 */

		d_set_d_op(dentry, &autofs4_root_dentry_operations);

		autofs4_expire_wait(expiring);

		autofs4_del_expiring(expiring);

		dput(expiring);

	}

	return 0;

}



static struct dentry *autofs4_mountpoint_changed(struct path *path)

{

	struct dentry *dentry = path->dentry;

	struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);



	/*

		 * And we need to ensure that the same dentry is used for

		 * all following lookup calls until it is hashed so that

		 * the dentry flags are persistent throughout the request.

	 * If this is an indirect mount the dentry could have gone away

	 * as a result of an expire and a new one created.

	 */

		ino = autofs4_init_ino(NULL, sbi, 0555);

		if (!ino)

			return ERR_PTR(-ENOMEM);

	if (autofs_type_indirect(sbi->type) && d_unhashed(dentry)) {

		struct dentry *parent = dentry->d_parent;

		struct dentry *new = d_lookup(parent, &dentry->d_name);

		if (!new)

			return NULL;

		dput(path->dentry);

		path->dentry = new;

	}

	return path->dentry;

}



		dentry->d_fsdata = ino;

		ino->dentry = dentry;

struct vfsmount *autofs4_d_automount(struct path *path)

{

	struct dentry *dentry = path->dentry;

	struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);

	struct autofs_info *ino = autofs4_dentry_ino(dentry);

	int status;



		autofs4_add_active(dentry);

	DPRINTK("dentry=%p %.*s",

		dentry, dentry->d_name.len, dentry->d_name.name);



		d_instantiate(dentry, NULL);

	}

	/* The daemon never triggers a mount. */

	if (autofs4_oz_mode(sbi))

		return NULL;



	if (!oz_mode) {

		mutex_unlock(&dir->i_mutex);

		expiring = autofs4_lookup_expiring(dentry);

		if (expiring) {

	/*

			 * If we are racing with expire the request might not

			 * be quite complete but the directory has been removed

			 * so it must have been successful, so just wait for it.

	 * If an expire request is pending everyone must wait.

	 * If the expire fails we're still mounted so continue

	 * the follow and return. A return of -EAGAIN (which only

	 * happens with indirect mounts) means the expire completed

	 * and the directory was removed, so just go ahead and try

	 * the mount.

	 */

			autofs4_expire_wait(expiring);

			autofs4_del_expiring(expiring);

			dput(expiring);

		}

	status = do_expire_wait(dentry);

	if (status && status != -EAGAIN)

		return NULL;



	/* Callback to the daemon to perform the mount or wait */

	spin_lock(&sbi->fs_lock);

		ino->flags |= AUTOFS_INF_PENDING;

	if (ino->flags & AUTOFS_INF_PENDING) {

		spin_unlock(&sbi->fs_lock);

		if (dentry->d_op && dentry->d_op->d_revalidate)

			(dentry->d_op->d_revalidate)(dentry, nd);

		mutex_lock(&dir->i_mutex);

		status = autofs4_mount_wait(dentry);

		if (status)

			return ERR_PTR(status);

		spin_lock(&sbi->fs_lock);

		goto done;

	}



	/*

	 * If we are still pending, check if we had to handle

	 * a signal. If so we can force a restart..

	 * If the dentry is a symlink it's equivalent to a directory

	 * having d_mounted() true, so there's no need to call back

	 * to the daemon.

	 */

	if (ino->flags & AUTOFS_INF_PENDING) {

		/* See if we were interrupted */

		if (signal_pending(current)) {

			sigset_t *sigset = &current->pending.signal;

			if (sigismember (sigset, SIGKILL) ||

			    sigismember (sigset, SIGQUIT) ||

			    sigismember (sigset, SIGINT)) {

			    if (active)

				dput(active);

			    return ERR_PTR(-ERESTARTNOINTR);

			}

		}

		if (!oz_mode) {

	if (dentry->d_inode && S_ISLNK(dentry->d_inode->i_mode))

		goto done;

	spin_lock(&dentry->d_lock);

	if (!d_mountpoint(dentry) && list_empty(&dentry->d_subdirs)) {

		ino->flags |= AUTOFS_INF_PENDING;

		spin_unlock(&dentry->d_lock);

		spin_unlock(&sbi->fs_lock);

		status = autofs4_mount_wait(dentry);

		if (status)

			return ERR_PTR(status);

		spin_lock(&sbi->fs_lock);

		ino->flags &= ~AUTOFS_INF_PENDING;

			spin_unlock(&sbi->fs_lock);

		}

		goto done;

	}



	/*

	 * If this dentry is unhashed, then we shouldn't honour this

	 * lookup.  Returning ENOENT here doesn't do the right thing

	 * for all system calls, but it should be OK for the operations

	 * we permit from an autofs.

	 */

	if (!oz_mode && d_unhashed(dentry)) {

	spin_unlock(&dentry->d_lock);

done:

	/*

		 * A user space application can (and has done in the past)

		 * remove and re-create this directory during the callback.

		 * This can leave us with an unhashed dentry, but a

		 * successful mount!  So we need to perform another

		 * cached lookup in case the dentry now exists.

	 * Any needed mounting has been completed and the path updated

	 * so turn this into a normal dentry so we don't continually

	 * call ->d_automount().

	 */

		struct dentry *parent = dentry->d_parent;

		struct dentry *new = d_lookup(parent, &dentry->d_name);

		if (new != NULL)

			dentry = new;

		else

			dentry = ERR_PTR(-ENOENT);

	managed_dentry_clear_automount(dentry);

	spin_unlock(&sbi->fs_lock);



		if (active)

			dput(active);

	/* Mount succeeded, check if we ended up with a new dentry */

	dentry = autofs4_mountpoint_changed(path);

	if (!dentry)

		return ERR_PTR(-ENOENT);



		return dentry;

	return NULL;

}



	if (active)

/* Lookups in the root directory */

static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)

{

	struct autofs_sb_info *sbi;

	struct autofs_info *ino;

	struct dentry *active;



	DPRINTK("name = %.*s", dentry->d_name.len, dentry->d_name.name);



	/* File name too long to exist */

	if (dentry->d_name.len > NAME_MAX)

		return ERR_PTR(-ENAMETOOLONG);



	sbi = autofs4_sbi(dir->i_sb);



	DPRINTK("pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d",

		current->pid, task_pgrp_nr(current), sbi->catatonic, oz_mode);



	active = autofs4_lookup_active(dentry);

	if (active) {

		return active;

	} else {

		d_set_d_op(dentry, &autofs4_root_dentry_operations);



		/*

		 * A dentry that is not within the root can never trigger a

		 * mount operation, unless the directory already exists, so we

		 * can return fail immediately.  The daemon however does need

		 * to create directories within the file system.

		 */

		if (!autofs4_oz_mode(sbi) && !IS_ROOT(dentry->d_parent))

			return ERR_PTR(-ENOENT);



		/* Mark entries in the root as mount triggers */

		if (autofs_type_indirect(sbi->type) && IS_ROOT(dentry->d_parent)) {

			d_set_d_op(dentry, &autofs4_dentry_operations);

			managed_dentry_set_automount(dentry);

		}



		ino = autofs4_init_ino(NULL, sbi, 0555);

		if (!ino)

			return ERR_PTR(-ENOMEM);



		dentry->d_fsdata = ino;

		ino->dentry = dentry;



		autofs4_add_active(dentry);



		d_instantiate(dentry, NULL);

	}

	return NULL;

}
@@ -715,11 +762,6 @@ static int autofs4_dir_symlink(struct inode *dir, 
	}

	d_add(dentry, inode);



	if (dir == dir->i_sb->s_root->d_inode)

		d_set_d_op(dentry, &autofs4_root_dentry_operations);

	else

		d_set_d_op(dentry, &autofs4_dentry_operations);



	dentry->d_fsdata = ino;

	ino->dentry = dget(dentry);

	atomic_inc(&ino->count);
@@ -850,11 +892,6 @@ static int autofs4_dir_mkdir(struct inode *dir, struct dentry *dentry, int mode) 
	}

	d_add(dentry, inode);



	if (dir == dir->i_sb->s_root->d_inode)

		d_set_d_op(dentry, &autofs4_root_dentry_operations);

	else

		d_set_d_op(dentry, &autofs4_dentry_operations);



	dentry->d_fsdata = ino;

	ino->dentry = dget(dentry);

	atomic_inc(&ino->count);